the original 7.25" (piece of ****) diff in my '72 Swinger had those oddball 10x1.75" flared "Bell" drums .
those bastards would have cost $75.00 a piece to replace , back in the mid-90's , AND there was a $25.00 core charge on them each (!!).
Why a core ? They can be relined .
So instead of paying a King's ransom for the stupid things , I just went to the local pick-a-part and grabbed an 8.25" diff (with 3.21 Sure Grip AND the all-important big bolt circle wheel pattern) and said 'good riddance' to that spindly , too-weak-even-for-a-170-Slant-Six-with-an-automatic 7.25" pile :mumum: .